Large Format Tile Installation: A Growing Problem?
April 15, 2008
Is tile having a growing problem? This month’s editorial calendar called for an article on Large Format Tile Installation. But just what does “large format tile” mean anymore? Historically it was defined as any tile with a size of 8”x 8” or larger, a definition that survives in print to this very day in the TCA Handbook. I think nearly everyone would agree it is relatively rare to see an 8”x 8” tile any more on the floor. In our conservative behind-the-times Wisconsin market area we hardly ever see even a 12” x12” tile anymore; 16” or 18” has become the standard and growing from there back home.
I spent a little time down the hall at the Tile Council of North America testing lab last week. They were contemplating how they were going to physically move and test a 4’x 4’ tile weighing in at 120 pounds for size variation. Typically they use a computerized table with sensors to measure an 80 tile array for warpage, thickness, and size variation required under standards. Unfortunately this tile is as larger than the entire table and will definitely take two big strong people to position once they figure out what they will be measuring it with. Bigger is here to stay, so I expect we will be seeing some new equipment real soon.
Technology has been kind to the tile manufacturing industry. The development of ever larger tile continues to grow at a rapid pace. It is hard to believe that only 30 years ago making 12”x12” tile was a challenge for many plants. Part of the rapid growth in tile size is due to the number of new plants built to service the growing industry demand for ceramic tile in general. These plants are able to use the very latest in technological advances. This allows for the highly sophisticated and tightly controlled manufacturing process needed for the manufacture of today’s most popular products. Control rooms today resemble a jumbo jet cockpit using digital controls to monitor the entire production process complete with digital read outs, flashing lights, and alarm sirens. Glazing technology has also developed to a point unimagined years ago. Those of you who have been to Surfaces or Coverings were no doubt fascinated by the vendors providing laser etchings of any photo image to a tile body. Currently, the technology exists to transfer a full color picture to tile utilizing a process where glazing is applied in a fashion similar to the ink jet process and then fired to achieve a light commercial rating. It seems the innovation in the ceramic tile manufacturing process has no bounds.
On the installation side of the equation, tile and related product manufacturers have remembered the installers too. As one would expect, setting material manufacturers have developed many new products to aid in bonding big tile. While traditional commodity type thinset products may provide attributes that are still adequate for larger tile, in some instances they often lack the enhanced values need for today’s installation environment. Items that warrant considered include but are not limited to; the type and condition of the substrate, the desired drying time prior to traffic, the flatness of the substrate, environmental conditions of the job-site and the in service use of the ceramic tile floor. These conditions may require use of highly engineered latex or polymer modified products to meet real world conditions. Grout product selection seems to be undergoing some transition as well. Many end users are demanding “stain proof” grouts or those that offer consistent color. When you combine this hi-tech large sized tile and the trend of minimal code compliant wood structures problems can easily arise. Concrete placement and finishing techniques can pose a challenge as well all of which brings us to our next consideration.
While tile size continues to grow, it unfortunately has not brought on any of the changes required by those who provide the substrates. Builders have not provided the flatter floors that such tile requires. In a perfect world, we would know ahead of time that we would be installing large tile and awareness of the more exacting tolerances for substrates could be specified in construction of the home or building. The reality is that this will seldom ever occur because tile selection is not part of the design process. Remodeling in older homes typically amplifies the problem and must meet existing finishes. Large tile requires what is known as super flat floors. The larger the tile, the flatter the floor. To create a floor with such flatness would require work way beyond the normal standards and recommendations of the substrate trades. Much like tile, the skill of the trades person, material needs, and often specialized equipment for this demanding type of work is at a premium if even available .The tile industry flatness recommendation of ¼” in 10’ was adapted and reflected in the tile industry recommendations from the published recommendations of the wood and cement trade organizations who have trade jurisdiction for their products. Unless specific tolerance requirements are established to accommodate large size tile prior to construction and properly implemented, it is safe to assume there will be preparation work required prior to tile installation when using any products larger than 12x12.
The method used for preparation should be carefully considered. Attempting to correct out-of-plane conditions with thinset while installing tile is very labor intensive and often results in an unsatisfactory installation. Thinset is not designed for truing work of others, i.e. carpenters and masons. The thickness required for filling even a minor dip can often leave the thinset very weak and incapable of good bonding or support. Using thinset to level a floor makes as much sense as building a road out of mortar instead of concrete; it just doesn’t work or won’t for long. Self-leveling products are often used to correct deficiency in floor flatness. The term self-leveling is somewhat misleading. From personal experience I can tell you to choose your words carefully when describing what floor remediation products and application you will be using.
Tile industry recommendations require a flat surface, regardless of level conditions. A level surface is one which the bubble is center in a level. A flat surface is one where no daylight is seen under a straight edge; there is a big difference in both application and the amount of product used. Unless there are large areas of repair required, a floor patch may often be preferable. This type of surface remediation (prep) is often where the contractor or installer suffers financial abuse in correcting the work of others. In our company we always found the best and easiest way to get compensated for our work was to make remediation (prep) a whole separate issue and return to install another day. Telling someone you will need to use a medium bed mortar and a lot more of it to correct a floor problem provides no visual satisfaction that there was indeed more work and consequently it is often difficult to collect your just rewards. Having a flat surface also speeds installation and reduces material needs enhancing profits. As a contractor we always made remediation (prep) a separate operation. This may be a little more challenging in the installer ranks depending on the structure of things, but it certainly is more profitable. And why do I keep saying remediation (prep)? Well, if you were a customer, which would you rather pay for, remediation of deficient substrates or floor prep? It is easier and more accurate to get paid for remediation.
The next challenge in large tile installation is selecting the appropriate bonding material. Selecting the appropriate thinset does not have to be a daunting task but you must consider both the site conditions and end use. It is difficult to describe all the reasons why you should use premium mortars suitable for jobsite conditions and expectations without going into a long, boring chemistry lesson. Later this year we will be doing an in-depth thinset article based on both testing and real-world performance. For now, suffice it to say, there is a difference and that difference is growing all the time. Setting materials have gotten very specialized for many good reasons. Larger tile can have extended initial cure times with standard thinsets. Covering more surface area, large tile should be installed with both a high bonding and flexible thinset. The consistency or the fluid movement ability of thinset is much more important when bedding large tile.
The considerations are many and more complex than many realize. Without argument the most important part of the process is making sure the tile is fully embedded in the thinset. Many often use a shortcut intended for non-wet walls called spot bonding. This has led to an ever increasing number of complaints for numerous reasons. Under certain conditions, spot bonding may work on walls given they are not expected to support loads. This is not true for floors which are load bearing surfaces. When troweling mortar for any application, the minor variation of the substrate and natural warpage of the tile or even the backing may mandate an application of mortar to the back of the tile, which is called backbuttering. Spot bonding is not appropriate for use regardless of whether back buttered or not. Based on phone calls and field visits for problems, it appears to be an increasingly popular method which is unfortunate once a claim is made.
The application and usage considerations of large unit tile are many. Such tile is often sold without regard for the inevitable substrate preparation required for satisfactory lippage-free installations. Small grout joints deserve consideration for the same reason: large tile’s inability to conform to floor irregularities. Even if the perfect substrate presents itself, tile will always have an inherent amount of warpage and size variation. There are products that will simply not lend themselves closely spaced flat floors under any conditions. Bottom line, tile should be chosen carefully with all its limitations fully understood. Setting materials deserve the same consideration and should be based on both environmental considerations and in service expectations. Chose wisely for happy customers and profitable installations.